Decline in resting spores of Plasmodiophora brassicae in soil over 6 years.

Citation

Gossen, B.D., Al-Daoud, F. Dumonceaux, T. Dalton, J. Peng, G. Pageau, D., and McDonald, M.R. 2018. Decline in resting spores of Plasmodiophora brassicae in soil over 6 years. International Clubroot Workshop (abstracts), https://www.canolacouncil.org/canola-encyclopedia/diseases/clubroot/research/, August 7 10, 2018, Edmonton, Pg. 12–13.

Résumé en langage clair

NA

Résumé

The concentration of resting spores of Plasmodiophora brassicae Wor. in a canola (Brassica napus L.) field has a major effect on clubroot severity and the risk of a breakdown in resistance. This study was carried out on soil samples collected from a long-term rotation study at Normandin, QC in 2014, with replicated plots representing a 0-, 1-, 2-, 3-, 5- or 6-year break following a susceptible canola crop heavily infested with clubroot. Five molecular techniques for estimating P. brassicae resting spores in soil were assessed, including quantitative polymerase chain reaction (qPCR), competitive internal positive control PCR (CIPC-PCR), droplet digital PCR (ddPCR), loop-mediated isothermal DNA amplification (LAMP), as well as propidium monoazide PCR (PMA-PCR) to assess spore viability. For several of the techniques, calibrations needed to be developed using spiked soil samples, where a known amount of resting spores were added. Each of the assays provided a similar pattern of spore decline over time. This result supported the conclusion of a previous study at this site, that resting spore numbers declined rapidly over the first 2 years after a susceptible crop, but the rate of decline was substantially lower in subsequent years (type III survival curve). CIPC-PCR and ddPCR provided better estimates of resting spore numbers in soil compared with those from qPCR alone or LAMP. Estimates of viable spores from PMA-PCR were much lower than the estimates of spore numbers from the other techniques in the first year, but were similar thereafter.

Date de publication

2018-12-31

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